CN101901607B - Objective lens, optical pickup apparatus, and optical information recording reproducing apparatus - Google Patents

Objective lens, optical pickup apparatus, and optical information recording reproducing apparatus Download PDF

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Publication number
CN101901607B
CN101901607B CN201010170114.2A CN201010170114A CN101901607B CN 101901607 B CN101901607 B CN 101901607B CN 201010170114 A CN201010170114 A CN 201010170114A CN 101901607 B CN101901607 B CN 101901607B
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China
Prior art keywords
light beam
base configuration
object lens
information recording
light quantity
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CN201010170114.2A
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CN101901607A (en
Inventor
中村健太郎
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Konica Minolta Opto Inc
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Konica Minolta Opto Inc
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1392—Means for controlling the beam wavefront, e.g. for correction of aberration
    • G11B7/13922—Means for controlling the beam wavefront, e.g. for correction of aberration passive
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1353—Diffractive elements, e.g. holograms or gratings
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372—Lenses
    • G11B7/1374—Objective lenses
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
    • G11B2007/0006—Recording, reproducing or erasing systems characterised by the structure or type of the carrier adapted for scanning different types of carrier, e.g. CD & DVD
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372—Lenses
    • G11B7/1376—Collimator lenses
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1392—Means for controlling the beam wavefront, e.g. for correction of aberration
    • G11B7/13925—Means for controlling the beam wavefront, e.g. for correction of aberration active, e.g. controlled by electrical or mechanical means

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Head (AREA)
  • Lenses (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)

Abstract

Disclosed are an optical pick-up device, an optical information recording/reproducing device, and an objective preferable therefor enabling achievement of compatibility among three types of optical discs, i.e., BDs, DVDs, and CDs by means of a common objective and enabling the working distance of the CDs to be adequately ensured. The objective has a first optical path difference imparting structure in the central region made by superimposing at least a first fundamental structure and a second fundamental structure one on the other and a second optical path difference imparting structure in the intermediate region made by superimposing at least a third fundamental structure, a fourth fundamental structure, and a fifth fundamental structure. The order of the diffracted light produced most frequently by the first fundamental structure is made equal to that produced by the third fundamental structure, and the order of the diffracted light produced most frequently by the second fundamental structure is made equal to that produced by the fourth fundamental structure. By the fifth fundamental structure, the zero-th order diffracted light is produced most frequently from a first light beam having a first wavelength, the zero-th order diffracted light is produced most frequently from a second light beam having a second wavelength, and the G-th order diffracted light is produced most frequently from a third light beam having a third wavelength.

Description

Object lens, optical take-up apparatus and optical information recording regenerator
Technical field
The present invention relates to exchange optical take-up apparatus, object lens and the optical information recording regenerator that carries out possibly information recording and/or regeneration (recording/reproducing) to different types of CD.
Background technology
In recent years, in optical take-up apparatus, as being used for the information of reproduced light disc recording and to the light source of cd-rom recording of information, the short wavelengthization of the LASER Light Source of using is made progress to some extent, for example, the LASER Light Source of bluish violet semiconductor laser equiwavelength 390～420nm is practical.Use the words of these bluish violet color laser light sources, when the object lens that use with the identical numerical aperture of DVD (digital universal disc) (NA), to the CD of diameter 12cm, can record the information of 15～20GB, the NA of object lens is brought up to at 0.85 o'clock, to the CD of diameter 12cm, can record the information of 23～25GB.
As the examples of optical disks of using above-mentioned NA0.85 object lens, can enumerate BD (Blu-ray Disc).Because the coma aberration that the skew in optical disc (skew) that results from occurs increases, so the protective substrate of BD designs than DVD also thin (only having 0.1mm with respect to the 0.6mm of DVD), reduces thus the crooked aberration amount causing.
But, only can be to BD recording/reproducing information correctly, also insufficient as the value of dvd playback/record machine (optical information recording regenerator) product.Consider to have now and recording the DVD of varied information and the present situation of CD (mini disk) sale, so, it is inadequate being merely able to BD recording/reproducing information, the DVD that for example user is held and CD be recording/reproducing information equally correctly also, is to improve as BD with the inevitable institute of CD playing/recording machine value of the product extremely.For this background, wish to be equipped on the dvd playback that BD uses/record the optical take-up apparatus in machine, both any interchangeability that maintains to BD, DVD and CD, had again the performance of recording/reproducing information definitely.
As the both any interchangeability that maintains to BD, DVD and CD, the method of recording/reproducing information definitely again, can consider according to the recording density of the CD of recording/reproducing, optionally switch the method for the optical system that optical system, DVD and CD that BD uses use, but because need a plurality of optical systems, so be unfavorable for miniaturization, cost rises in addition.
Therefore, in order to simplify optical take-up apparatus structure, realize low-costly, the optical system that preferably also makes optical system that BD uses and DVD, CD use in having the optical take-up apparatus of interchangeability is general, to reduce the optics number that forms optical take-up apparatus as far as possible.Yet, making the object lens universalization facing to CD configuration, this is the most favourable to simplifying optical take-up apparatus structure and reducing costs.In order to obtain, to the mutual different general object lens of multiple kinds of optical disc of recording/reproducing wavelength, must forming the diffraction structure of the wavelength interdependence with spherical aberration on object lens.
Be common to the object lens of BD, DVD, CD3 kind CD, numerical aperture that must be required with BD, DVD, CD is corresponding.For example, during the large BD of required numerical aperture, make through the effective optical surface of object lens almost the beam condenser in whole region on the information recording surface of BD, and when the little CD of required numerical aperture, be to make beam condenser through object lens central authorities near zone on the information recording surface of CD, but the information recording surface Shangdi that is necessary to make light beam through its exterior lateral area not to be concentrated on CD disperse as solar flare.Therefore, be common to the object lens of BD, DVD, CD3 kind CD as shown in Figure 1, its optical surface is divided into 3 regions (optically focused BD, DVD, CD use the neighboring area OT of light beam with middle section CN, optically focused BD and the DVD of light beam with zone line MD, the optically focused BD of light beam) of concentric circles, is necessary to make to show in regional the movement of different optical performance.
But, know, it is difficult making specific 2 wavelength phase deviation does not occur maintain optical property at the middle section of above-mentioned object lens and zone line.
To this, a kind of object lens and the optical take-up apparatus that has carried these object lens in patent documentation 1, have been recorded, wherein, by making the diffraction number of times of two base configurations overlapping on middle section, identical with the diffraction number of times of two base configurations overlapping on zone line, thus the phase deviation problem that solution has disappeared between middle section and zone line.
But, according to the design of the HD DVD, the DVD that record in patent documentation 1 embodiment and CD exchange object lens, designed BD, DVD and CD and exchanged object lens, but found that CD always has not light to produce harmful effect to optically focused spot while using, be difficult to carry out good information recording/regeneration.
Look-ahead technique document
Patent documentation
Patent documentation 1: JP 2008-293630 communique
Summary of the invention
The problem that invention wish solves
The present invention be take and solved above-mentioned problem as object, object is the object lens that a kind of optical take-up apparatus, optical information recording regenerator are provided and are applicable to them, wherein, can carry out the exchange of BD, DVD and CD3 kind CD by enough general object lens, and prevent from producing phase deviation between middle section and zone line, and CD while using not light optically focused spot is produced to harmful effect, can carry out stable information recording/regeneration.
By the means that solve problem
The object lens that technical scheme 1 is recorded, for thering is the 1st light source of the 1st light beam that penetrates the 1st wavelength X 1, penetrate the 2nd light source of the 2nd light beam of the 2nd wavelength X 2 (λ 2 > λ 1), penetrate the 3rd light source of the 3rd light beam of the 3rd wavelength X 3 (λ 3 > λ 2), and there is with described the 1st light beam information recording and/or the regeneration of the 1st CD that thickness is the protective substrate of t1, with described the 2nd light beam, there is information recording and/or the regeneration of the 2nd CD that thickness is the protective substrate of t2 (t1 < t2), with described the 3rd light beam, there are the 3rd information recording of CD of protective substrate that thickness is t3 (t2 < t3) and/or the object lens of the optical take-up apparatus of regeneration, it is characterized in that, the optical surface of described object lens at least has middle section, the zone line of described its central area, described zone line neighboring area around, described middle section has the 1st optical path difference and pays structure, described zone line has the 2nd optical path difference and pays structure, described object lens by can information recording through described the 1st light beam of described middle section and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 1st CD, by can information recording through described the 2nd light beam of described middle section and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 2nd CD, by can information recording through described the 3rd light beam of described middle section and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 3rd CD, described object lens by can information recording through described the 1st light beam of described zone line and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 1st CD, by can information recording through described the 2nd light beam of described zone line and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 2nd CD, not by can information recording through described the 3rd light beam of described zone line and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 3rd CD, described object lens by can information recording through described the 1st light beam of described neighboring area and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 1st CD, not by can information recording through described the 2nd light beam of described neighboring area and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 2nd CD, not by can information recording through described the 3rd light beam of described neighboring area and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 3rd CD, it is at least to overlap the structure of the 1st base configuration and the 2nd base configuration that described the 1st optical path difference is paid structure, described the 1st base configuration makes to be greater than through the diffraction light quantity of X time of the 1st light beam of described the 1st base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of Y time of the 2nd light beam of described the 1st base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of Z time of the 3rd light beam of described the 1st base configuration the diffraction light quantity of other any number of times, described the 2nd base configuration makes to be greater than through the diffraction light quantity of L time of the 1st light beam of described the 2nd base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of M time of the 2nd light beam of described the 2nd base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of N time of the 3rd light beam of described the 2nd base configuration the diffraction light quantity of other any number of times, it is at least to overlap the structure of the 3rd base configuration and the 4th base configuration and the 5th base configuration that described the 2nd optical path difference is paid structure, described the 3rd base configuration makes to be greater than through the diffraction light quantity of A time of the 1st light beam of described the 3rd base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of B time of the 2nd light beam of described the 3rd base configuration the diffraction light quantity of other any number of times, described the 4th base configuration makes to be greater than through the diffraction light quantity of D time of the 1st light beam of described the 4th base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of E time of the 2nd light beam of described the 4th base configuration the diffraction light quantity of other any number of times, described the 5th base configuration makes to be greater than through the diffraction light quantity of 0 time of the 1st light beam of described the 5th base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of 0 time of the 2nd light beam of described the 5th base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of G time of the 3rd light beam of described the 5th base configuration the diffraction light quantity of other any number of times, X, Y, Z, L, M, N, A, B, D and E are integers, G is the integer beyond 0, meet following formula:
X＝A (15)
Y＝B (16)
L＝D (17)
M＝E (18)。
Present inventor finds, thereby disappearing in the object lens of the phase deviation problem between middle section and zone line by making to overlap the diffraction number of times of two base configurations of middle section and the identical solution of diffraction number of times that overlaps two base configurations of zone line, when the CD in the exchange of BD, DVD and CD3 kind CD is used is used, always there is the problem that light does not produce harmful effect, is difficult to carry out good information recording/regeneration optically focused spot.In order to address this problem, present inventor finds, on the 3rd base configuration and the 4th base configuration of zone line, as the 5th base configuration, overlappingly again make the 1st light beam produce maximum 0 diffraction light, make the 2nd light beam also produce maximum 0 diffraction light, make the 3rd light beam produce the structure of maximum G diffraction lights, thus, when solution disappears the phase deviation problem of middle section and zone line, in being used, the exchange of BD, DVD and CD3 kind CD can prevent that CD from not wanting light optically focused spot is produced to harmful effect while using.
In addition, even if overlapping the 5th base configuration also can provide the object lens of the light utilization ratio that also can remain high when BD and DVD.
The object lens that technical scheme 2 is recorded, are the inventions of recording in technical scheme 1, it is characterized in that, meet following formula:
G＝±1 (23)。
The object lens that technical scheme 3 is recorded, are the inventions of recording in technical scheme 1 or 2, it is characterized in that, described the 5th base configuration is 2 grades of notch cuttype structures.
The object lens that technical scheme 4 is recorded, are the inventions of recording in technical scheme 3, it is characterized in that, described 2 notch cuttypes structures have the step of the optical path difference that 5 wavelength that described the 1st light beam is provided to described the 1st wavelength X 1 divide.
The optical path difference that 5 wavelength that described the 1st light beam provided to the 1st wavelength X 1 by 2 grades of notch cuttype structures divide, the not harmful effect of light in the time of can reducing CD recording/reproducing greatlyr, so preferably.
The object lens that technical scheme 5 is recorded, are the inventions of recording in technical scheme 3, it is characterized in that, described 2 notch cuttypes structures have the step of the optical path difference that 3 wavelength that described the 1st light beam is provided to described the 1st wavelength X 1 divide.
The optical path difference that 3 wavelength that described the 1st light beam provided to the 1st wavelength X 1 by 2 grades of notch cuttypes structure divide, can reduce the height of the 5th base configuration, easily manufactures, and can reduce and manufacture loss, furthermore, can prevent the reduction of light utilization ratio, so preferably.In addition, because the change of the diffraction efficiency can be by wavelength variation time suppresses for less, so preferred.
The object lens that technical scheme 6 is recorded, are the inventions of recording in any one of technical scheme 3 to 5, it is characterized in that, on the upper flat table top of described 2 grades of notch cuttypes structure, having the step of single described the 4th base configuration and a plurality of described the 3rd base configurations.
By establishing the step of a plurality of the 3rd base configurations on the upper flat table top at 2 grades of notch cuttype structures, resin easily arrives the die tip of 2 grades of notch cuttype structures, can improve transfer printing and reduce and manufacture loss, can prevent the reduction of light utilization ratio.And, can make the spot position of diffraction light not, more leave the spot position of necessary diffraction light, can prevent that diffraction light optically focused not from producing flase drop and going out on photo detector, preferably.
The object lens that technical scheme 7 is recorded, are the inventions of recording in any one of technical scheme 3 to 6, it is characterized in that, the minimum tooth of described the 5th base configuration is apart from more than 10 μ m.
The object lens that technical scheme 8 is recorded, are the inventions of recording in any one of technical scheme 1 to 7, it is characterized in that, described L and D are even numbers, and described X and A are odd numbers.
The object lens that technical scheme 9 is recorded, are the inventions of recording in technical scheme 8, it is characterized in that, described L and D be absolute value at the even number below 4, described X and A are that absolute value is at the odd number below 5.
The object lens that technical scheme 10 is recorded, it is the invention of recording in any one of technical scheme 1 to 9, it is characterized in that, described the 1st base configuration, described the 2nd base configuration, described the 3rd base configuration and described the 4th base configuration are flame type structures, at least be located near described the 1st base configuration of optical axis of described middle section, its step, towards the contrary direction of optical axis, is at least located near described the 2nd base configuration of optical axis of described middle section, and its step is towards the direction of optical axis.
The object lens that technical scheme 11 is recorded, it is the invention of recording in technical scheme 10, it is characterized in that, described the 1st base configuration and described the 3rd base configuration, their all steps are all towards optical axis reverse direction, described the 2nd base configuration and described the 4th base configuration, their all steps are all towards optical axis direction.
The object lens that technical scheme 12 is recorded, are the inventions of recording in any one of technical scheme 1 to 11, it is characterized in that, formula meets the following conditions:
1.0≤d/f≤1.5 (3)
Wherein, d represents the thickness (mm) on the optical axis of described object lens, when f represents described the 1st light beam described in the focal length of object lens.
When object lens are used for the CD of the such short wavelength of BD, high NA, exist astigmatism and the easy problem that eccentric coma aberration occurs easily occur, but by said structure, can suppress the generation of astigmatism and eccentric coma aberration.
The object lens that technical scheme 13 is recorded, are the inventions of recording in any one of technical scheme 1 to 12, it is characterized in that, formula meets the following conditions:
-0.01＜m1＜0.01 (4)
-0.01＜m2＜0.01 (5)
-0.01＜m3＜0.01 (6)
Wherein, when m1 represents that described the 1st light beam incides described object lens described in the multiplying power of object lens, when m2 represents that described the 2nd light beam incides described object lens described in the multiplying power of object lens, when m3 represents that described the 3rd light beam incides described object lens described in the multiplying power of object lens.
The optical take-up apparatus that technical scheme 14 is recorded, is characterized in that, has the object lens of recording in any one of technical scheme 1 to 13.
The optical information recording regenerator that technical scheme 15 is recorded, is characterized in that, has the optical take-up apparatus of recording in technical scheme 14.
Optical take-up apparatus of the present invention has at least 3 light sources of the 1st light source, the 2nd light source, the 3rd light source.And, optical take-up apparatus of the present invention have for make the 1st beam condenser on the information recording surface of the 1st CD, make the 2nd beam condenser on the information recording surface of the 2nd CD, make the light-gathering optics of the 3rd beam condenser on the information recording surface of the 3rd CD.In addition, optical take-up apparatus of the present invention has the photo detector of the folded light beam of the information recording surface of accepting the 1st CD, the 2nd CD and the 3rd CD.
The 1st CD has protective substrate and the information recording surface that thickness is t1.The 2nd CD has protective substrate and the information recording surface that thickness is t2 (t1 < t2).It is t3 (t2 < t3) protective substrate and information recording surface that the 3rd CD has thickness.Preferably the 1st CD is that BD, the 2nd CD are that DVD, the 3rd CD are CD, but are not limited to this.And the 1st CD, the 2nd CD or the 3rd CD can be also the multiplayer optical disks with a plurality of information recording surfaces.
In this instructions; BD is the general name that the object lens by the light beam of wavelength 390～415nm degree, NA0.8～0.9 degree carry out the BD series CD that thickness information recording/regeneration, protective substrate is 0.05～0.125mm degree, comprises the BD etc. that only has the BD of single piece of information recording layer and have 2 layers or its above information recording layer.And; in this instructions; DVD is carried out the general name of the DVD series CD that thickness information recording/regeneration, protective substrate is 0.6mm degree by the object lens of NA0.60～0.67 degree, comprise DVD-ROM, DVD-Video, DVD-Audio, DVD-RAM, DVD-R, DVD-RW, DVD+R, DVD+RW etc.In addition, in this instructions, CD is carried out the general name of the CD series CD that thickness information recording/regeneration, protective substrate is 1.2mm degree by the object lens of NA0.45～0.51 degree, comprise CD-ROM, CD-Audio, CD-Video, CD-R, CD-RW etc.Relevant recording density, the recording density of BD is the highest, subsequent with DVD, CD order successively reduction.
The thickness t 1 of relevant protective substrate, t2, t3, the formula that preferably meets the following conditions (7), (8), (9), but be not limited to this.Here the thickness of said protective substrate, is provided in a side of the thickness of the protective substrate of optical disc surface.Refer to from optical disc surface to the thickness of protective substrate that approaches most the information recording surface on surface.
0.050mm≤t1≤0.125mm (7)
0.5mm≤t2≤0.7mm (8)
1.0mm≤t3≤1.3mm (9)
In this instructions, preferably the 1st light source, the 2nd light source, the 3rd light source are LASER Light Source.As LASER Light Source, preferably adopt semiconductor laser, silicon laser etc.The 3rd wavelength X 3 (the λ 3 > λ 2) formula that meets the following conditions (10), (11) of the 2nd wavelength X 2 (λ 2 > λ 1) of the 2nd light beam that the 1st wavelength X the 1, the 2nd light source of the 1st light beam that preferably the 1st light source penetrates penetrates, the 3rd light beam that the 3rd light source penetrates:
1.5λ1＜λ2＜1.7λ1 (10)
1.8λ1＜λ3＜2.0λ1 (11)。
In addition, while using respectively BD, DVD and CD as the 1st CD, the 2nd CD, the 3rd CD, the 1st wavelength X 1 of the 1st light source is preferably below the above 440nm of 350nm, more preferably below the above 415nm of 390nm, the 2nd wavelength X 2 of the 2nd light source is preferably below the above 680nm of 570nm, more preferably, below the above 670nm of 630nm, the 3rd wavelength X 3 of the 3rd light source is preferably below the above 880nm of 750nm, more preferably below the above 820nm of 760nm.
It is dangerous that LASER Light Source is that the words of carrying out the overlapping type of high frequency are crosstalked etc., but by making chromatic aberation on axle below 0.9 μ m/nm, carry out that even above-mentioned the overlapping LASER Light Source of high frequency also can prevent to crosstalk etc., therefore preferably.In addition, if the LASER Light Source (3 light sources that optimal wavelength different whole) of the half value overall with (peak value half the overall with of wave spectrum) that adopts the wave spectrum of outgoing beam more than 0.5nm, the problem such as crosstalk is larger, but by making on axle chromatic aberation below 0.9 μ m/nm, can not be a problem and use, therefore preferably.
Can be at least 2 light source cells in the 1st light source, the 2nd light source, the 3rd light source.So-called blocking refers to that for example the 1st light source and the 2nd light source are fixed and is accommodated in 1 plug-in unit.Except light source, after the photo detector that will narrate also can 1 plug-in unit.
As photo detector, preferably adopt the optical detectors such as photodiode.The light reflecting on optical disc information record surface incides photo detector, can obtain the read signal of recorded information on each CD by its output signal.And, detect that spot shape on photo detector changes, the light quantity of change in location changes to focus to detect with track and detect, can detect mobile object lens according to this and focus and follow the tracks of.Photo detector can consist of a plurality of optical detectors.Photo detector also can have main optical detector and secondary optical detector.Can form following photo detector, for example, in acceptance, for the both sides of the optical detector of the key light of information recording/regeneration, establish 2 secondary optical detectors, by these 2 secondary optical detectors, accept to follow the tracks of the secondary light of adjusting use.Photo detector also can have a plurality of photo detectors corresponding with each light source.
Light-gathering optics has object lens.Preferably light-gathering optics also has the coupled lens such as collimator except object lens.Coupled lens refers to simple lens or the lens combination of the change beam divergence angle being configured between object lens and light source.Collimator is a kind of of coupled lens, is the light that incides collimator is become to the lens that directional light penetrates.In this instructions, object lens refer to and in optical take-up apparatus, are configured in facing to optical system in CD position, that have the function in the information recording surface of CD by the beam condenser penetrating from light source.Object lens can consist of two above a plurality of lens and/or optical elements, also can only single lens, consist of, preferably single lens.Can preferably adopt biconvex single lens.Object lens can be that glass lens can be also plastic lens, can also be with light-cured resin, UV curable resin or heat-curing resin etc., to have established the hybrid lens that optical path difference is paid structure on glass lens.When object lens have a plurality of lens, can mix and adopt glass lens and plastic lens.When object lens have a plurality of lens, can be also to there is the combination that optical path difference is paid planar optics element and the non-spherical lens (can have and also can not have optical path difference to pay structure) of structure.In addition, preferably the plane of refraction of object lens is aspheric surfaces.Also preferably object lens are provided with optical path difference to pay the basal plane of structure are aspheric surfaces.
While making object lens be glass lens, preferably use glass branchpoint Tg below 500 ℃, more preferably at the glass material below 400 ℃.By using glass branchpoint Tg at the glass material below 500 ℃, the enough lower temperature moulding of energy, can extend die life.As the low glass material of this glass branchpoint Tg, there are K-PG325, K-PG375 (being all name of product) that for example Sumita Optical Glass Co., Ltd. manufactures.
But in general glass lens proportion is larger than resin lens, so making object lens is the words weight rising of glass lens, the burden of the gearing of driving object lens is large.While therefore, making object lens be glass lens, preferably use the glass material that proportion is little.Concrete preferred specific gravity is below 4.0, and more preferably proportion is below 3.0.
When in addition, glass lens is made in moulding, linear expansion coefficient a is an important physics value.Even selected Tg, be 400 ℃ of following materials, still the temperature difference of room temperature and plastic material is still very large by contrast.During with the large glass molding material lens of linear expansion coefficient a, during cooling, easily there is crack.The linear expansion coefficient a of preferred glass material is below 200 (10E-7/K), more preferably below 120.
While making object lens be plastic lens, preferably use the ester ring type hydrocarbon polymer materials such as resin material of cyclic polyolefin hydro carbons.In this resin material, more preferably use again when 25 ℃ of temperature the refractive index of wavelength wavelength 405nm in 1.54 to 1.60 scopes, in the temperature range of-5 ℃ to 70 ℃, follow temperature variation to the variations in refractive index rate dN/dT of wavelength 405nm (℃ -1)-20 * 10 -5to-5 * 10 -5(more preferably-10 * 10 -5to-8 * 10 -5) resin material in scope.In addition, while making object lens be plastic lens, preferably making coupled lens is also plastic lens.
Below enumerate the preferred embodiment of several ester ring type hydrocarbon polymers.
The 1st preferred embodiment relates to the resin combination that comprises following segmented copolymer: described segmented copolymer has polymer blocks [A] and polymer blocks [B], described polymer blocks [A] comprises the repetitive [1] that following formula (I) represents, described polymer blocks [B] comprises the repetitive [1] that following formula (1) represents, and the repetitive [3] that the repetitive [2] that comprises following formula (II) expression and/or following formula (III) represent, and the mole fraction a of the repetitive [1] in above-mentioned block [A] (% by mole) and above-mentioned block [B] in repetitive [1] mole fraction b (% by mole) between pass be a > b.
[Chemical formula 1]
(in formula, R 1represent the alkyl of hydrogen atom or carbon number 1～20, R 2-R 12represent independently of one another alkyl, the hydroxyl of hydrogen atom, carbon number 1～20, alkoxy or the halogen group of carbon number 1～20.)
[Chemical formula 2]
(in formula, R 13represent the alkyl of hydrogen atom or carbon number 1～20.)
[chemical formula 3]
(in formula, R 14and R 15represent independently of one another the alkyl of hydrogen atom or carbon number 1～20.)
In addition, the 2nd preferred embodiment relates to the resin combination that comprises following polymkeric substance (A) and following polymkeric substance (B): described polymkeric substance (A) is to be that 2～20 alpha-olefin and the monomer composition that comprises the cyclic olefin that following general formula (IV) represents carry out the polymkeric substance that addition polymerization obtains by least making carbon number; Described polymkeric substance (B) is that the monomer composition that makes the alpha-olefin of carbon number 2～20 and comprise the cyclic olefin that following general formula (V) represents carries out addition polymerization and the polymkeric substance that obtains.
[chemical formula 4]
General formula (IV)
[in formula, n be 0 or 1, m be more than 0 or 1 integer, q is 0 or 1, R 1～R 18, R aand R brepresent independently of one another hydrogen atom, halogen atom or alkyl, R 15～R 18bonding forms monocycle or encircles more mutually, and the monocycle in bracket or many rings can have two keys, in addition, and R 15and R 16can form alkylidene or R 17and R 18can form alkylidene.]
[chemical formula 5]
General formula (IV)
[in formula, R 19～R 26represent independently of one another hydrogen atom, halogen atom or alkyl.]
For further, for resin material is given performance, can also add wherein adjuvant as follows.
(stabilizing agent)
Preferably add and be selected from least a kind of stabilizing agent in phenol stabilizer, hindered amines stabilizing agent, Phosphorus stabilizing agent and sulphur class stabilizing agent.By suitable selection and add these stabilizing agents, for example, the variation of the optical characteristics such as the muddiness producing in the time of can be to the such short-wavelength light of prolonged exposure 405nm, variations in refractive index realizes more efficiently inhibition.
As preferred phenol stabilizer, can use the stabilizing agent of conventional known, for example can enumerate: the acrylic acid 2-tert-butyl group-6-(the 3-tert-butyl group-2-hydroxy-5-methyl base benzyl)-4-methyl phenyl ester, acrylic acid 2,4-bis-tertiary pentyls-6-(1-(3,5-, bis-tertiary pentyls-2-hydroxyphenyl) ethyl) phenyl ester etc. is recorded in the acrylic ester compound in Japanese kokai publication sho 63-179953 communique, Japanese kokai publication hei 1-168643 communique, propionic acid octadecyl-3-(3, 5-di-t-butyl-4-hydroxyphenyl) ester, 2, 2 '-di-2-ethylhexylphosphine oxide (4-methyl-6-tert-butylphenol), 1, 1, 3-tri-(2-methyl-4-hydroxyl-5-tert-butyl-phenyl) butane, 1, 3, 5-trimethyl-2, 4, 6-tri-(3, 5-di-tert-butyl-4-hydroxyl benzyl) benzene, four (methylene-3-(3 ', 5 '-di-t-butyl-4 '-hydroxyphenylpropionic acid ester)) methane [, (3-(3 for pentaerythrite four, 5-di-t-butyl-4-hydroxyphenylpropionic acid ester))], the phenolic compound that the alkyl such as triethylene-glycol two (3-(3-tertiary butyl-4-hydroxy-5-aminomethyl phenyl) propionic ester) replace, 6-(4-hydroxyl-3,5-di-tert-butyl amido)-2, two pungent sulfenyl-1 of 4-, 3,5-triazine, the two pungent sulfenyl-1,3,5-triazines of 4-, pungent sulfenyl-4 of 2-, 6-two (3,5-di-t-butyl-4-hydroxy benzenes amido)-phenolic compound that 1,3,5-triazines etc. contains triazinyl, etc..
In addition, as preferred hindered amines stabilizing agent, can enumerate: decanedioic acid two (2, 2, 6, 6-tetramethyl-4-piperidyl) ester, succinic acid two (2, 2, 6, 6-tetramethyl-4-piperidyl) ester, decanedioic acid two (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) ester, two (N-octyloxy-2 of decanedioic acid, 2, 6, 6-tetramethyl-4-piperidyl) ester, two (N-benzyloxy-2 of decanedioic acid, 2, 6, 6-tetramethyl-4-piperidyl) ester, two (N-cyclohexyloxy-2 of decanedioic acid, 2, 6, 6-tetramethyl-4-piperidyl) ester, 2-(3, 5-di-tert-butyl-4-hydroxyl benzyl)-2-butylmalonic acid two (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) ester, 2, 2-two (3, 5-di-tert-butyl-4-hydroxyl benzyl) two (1-acryloyl group-2 of-2-butylmalonic acid, 2, 6, 6-tetramethyl-4-piperidyl) ester, decanedioic acid two (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) ester, methacrylic acid 2, 2, 6, 6-tetramethyl-4-piperidine ester, 4-[3-(3, 5-di-t-butyl-4-hydroxyphenyl) propionyloxy] (3-(3 for-1-[2-, 5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl]-2, 2, 6, 6-tetramethyl piperidine, 2-methyl-2-(2, 2, 6, 6-tetramethyl-4-piperidyl) amino-N-(2, 2, 6, 6-tetramethyl-4-piperidyl) propionamide, 1, 2, 3, 4-ethylene-dimalonic acid four (2, 2, 6, 6-tetramethyl-4-piperidyl) ester, 1, 2, 3, 4-ethylene-dimalonic acid four (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) ester etc.
In addition, as preferred Phosphorus stabilizing agent, so long as the stabilizer being normally used in conventional Resin Industry there is no particular restriction, for example can enumerate: triphenyl phosphite, phosphorous acid diphenyl isodecyl ester, diisodecyl phenyl phosphite, tricresyl phosphite (nonyl phenyl) ester, tricresyl phosphite (dinonyl phenyl) ester, tricresyl phosphite (2,4-di-tert-butyl-phenyl) ester, 10-(3,5-di-tert-butyl-4-hydroxyl benzyl)-single phosphite ester compounds such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 4,4 '-butylidene-bis-(3-methyl-6-tert butyl phenyl-bis-(tridecyl) phosphite ester), 4, the diphosphorous acid ester type compounds such as 4 '-isopropylidene-bis-(phenyl-dialkyl group (C12～C15) phosphite ester) etc.Wherein, preferred single phosphite ester compound, especially preferably tricresyl phosphite (nonyl phenyl) ester, tricresyl phosphite (dinonyl phenyl) ester, tricresyl phosphite (2,4-di-tert-butyl-phenyl) ester etc.
In addition, as preferred sulphur class stabilizing agent, for example can enumerate: 3,3-dilauryl thiodipropionate, 3,3 '-thio-2 acid, two myristins, 3,3-distearylthiodi-propionate, 3,3-thio-2 acid lauryl stearyl, pentaerythrite four (β-lauryl sulfo-) propionic ester, 3, two (the 2-dodecane sulfenyl ethyls)-2 of 9-, 4,8,10-, tetra-oxygen spiral shell [5,5] undecanes etc.
As the combined amount of above-mentioned each stabilizing agent, can be in the scope of not destroying object of the present invention suitably select, but with respect to ester ring type hydrocarbon type copolymer 100 mass parts, conventionally mix 0.01～2 mass parts, preferred 0.01～1 mass parts.
(surfactant)
Surfactant is in same a part, to have the compound of hydrophilic group and hydrophobic group.By utilizing surfactant, to attachment of moisture, speed and the moisture in resin surface regulates from the speed of above-mentioned surface evaporation, can prevent the gonorrhoea of resin combination.
As the hydrophilic group of surfactant, specifically can enumerate: more than 1 hydroxy alkyl of hydroxyl, carbon number, hydroxyl, carbonyl, ester group, amino, amide group, ammonium salt, mercaptan, sulfonate, phosphate, poly alkylene glycol base etc.Wherein, amino can be any in primary amino radical, secondary amino group, tertiary amino.As the hydrophobic group of surfactant, specifically can enumerate: more than 6 alkyl of carbon number, the silicyl with more than 6 alkyl of carbon number, more than 6 fluoro-alkyl of carbon number etc.Wherein, on more than 6 alkyl of carbon number, can also there is aromatic rings as its substituting group.As alkyl, specifically can enumerate: hexyl, heptyl, octyl group, nonyl, decyl, undecyl, dodecyl, tridecyl, myristyl, myristyl, stearyl, lauryl, palmityl, cyclohexyl etc.As aromatic rings, can enumerate phenyl etc.In this surfactant, can in same a part, there is each at least 1 in hydrophilic group as above and hydrophobic group, also can there are 2 each above groups.
As this class surfactant, more specifically, for example can enumerate: myristyl diethanolamine, 2-hydroxyethyl-2-hydroxyl lauryl amine, 2-hydroxyethyl-2-hydroxyl tridecyl base amine, 2-hydroxyethyl-2-hydroxyl tetradecylamine, pentaerythritol monostearate, pentaerythritol stearic acid ester 2, pentaerythrite tristearate, two (2-hydroxyethyl-2-hydroxyl dodecyl) amine, alkyl (carbon number 8～18) benzyl dimethyl ammonium chloride, ethylenebis alkyl (carbon number 8～18) acid amides, stearyl diglycollic amide, lauryl diglycollic amide, myristyl diglycollic amide, palmityl diglycollic amide etc.Wherein, preferably use amines or the amide compound with hydroxy alkyl.In the present invention, also above-claimed cpd of more than two kinds can be used in combination.
As surfactant, the angle of the molding gonorrhoea causing from can effectively suppressing to follow temperature, humidity to change, the height transmittance that keeps molding is considered, with respect to 100 mass parts ester ring type hydrocarbon polymers, preferably add the surfactant of 0.01～10 mass parts.With respect to 100 mass parts ester ring type hydrocarbon polymers, the addition of surfactant is 0.05～5 mass parts more preferably, further preferred 0.3～3 mass parts.
(plastifier)
Plastifier is in order to regulate the melt index (MI) of multipolymer, adds as required.
As plastifier, can adopt two (2-ethylhexyl) esters of hexane diacid, two (2-butoxyethyl group) esters of hexane diacid, two (2-ethylhexyl) esters of azelaic acid, dipropylene glycol dibenzoate, tri-n-butyl citrate, ATBC, epoxidised soybean oil, 2-ethylhexyl epoxidation tall oil, chlorinated paraffin, tri-2-ethylhexyl phosphate, tricresyl phosphate, phosphoric acid tert-butyl phenyl ester, tricresyl phosphate (2-ethylhexyl biphenyl) ester, dibutyl phthalate, o-phthalic acid ester, dibutyl phthalate (DHP), dinonyl phthalate, phthalic acid two (undecyl) ester, phthalic acid two (2-ethylhexyl) ester, diisononyl phthalate, diisooctyl phthalate, phthalic acid two (tridecyl) ester, butyl benzyl phthalate, dicyclohexyl phthalate, decanedioic acid two (2-ethylhexyl) ester, tri trimellitate (2-ethylhexyl) ester, Santicizer 278, Paraplex G40, Drapex 334F, Plastolein 9720, Mesamoll, DNODP-610, the known plastifier such as HB-40.The selection of plastifier and addition are suitably selected under can be not destroying the permeability of multipolymer, to the condition of the patience of environmental change.
As above-mentioned resin, be applicable to adopting cyclenes resin, specifically as preferred example, can enumerate ZEONEX that Japanese ゼオ Application company manufactures, APEL that Mitsui Chemicals, Inc. manufactures, the TOPAS that TOPAS ADVANCED POLYMERS company manufactures, the ARTON that JSR company manufactures etc.
In addition, the Abbe number of material that preferably forms object lens is more than 50.
Relevant object lens are described below.At least one optical surface of object lens, at least has the zone line of middle section, its central area, the neighboring area around zone line.Preferably middle section is the region containing objective lens optical axis, but also can be using the tiny area containing optical axis as not using region and specific use region, take that it is middle section around.Preferably middle section, zone line and neighboring area are arranged on same optical surface.Preferably as shown in Figure 1, middle section CN, zone line MD, neighboring area OT are arranged on same optical surface, are the concentric circles centered by optical axis.In addition, the middle section of object lens is provided with the first optical path difference and pays structure, and zone line is provided with the second optical path difference and pays structure.Neighboring area can be plane of refraction, also can establish in neighboring area the 3rd optical path difference and pay structure.Preferred middle section, zone line, neighboring area adjacency respectively, but between also can be slightly gapped.
The middle section of object lens can be described as for the 1st CD, the 2nd CD and the 3rd video disc recording/regeneration the 1st, the 2nd, the common area of the 3rd CD.That is to say, object lens by can information recording through the 1st light beam of middle section/again the dried rhizome of rehmannia be concentrated on the information recording surface of the 1st CD, by the 2nd light beam through middle section can information recording and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of the 2nd CD, by through middle section the 3rd light beam can information recording/dried rhizome of rehmannia be concentrated on the information recording surface of described the 3rd CD again.In addition; the 1st optical path difference that is preferably located at middle section is paid structure; to pay the 1st light beam and the 2nd light beam of structure through the 1st optical path difference, revise due to the different spherical aberrations that produce of the 1st CD protecting substrate thickness t1 and the 2nd CD protecting substrate thickness t2 or due to the different spherical aberrations that produce of wavelength of the 1st light beam and the 2nd light beam.And; preferably the 1st optical path difference is paid structure to pay the 1st light beam and the 3rd light beam of structure through the 1st optical path difference, revises different spherical aberrations that produce due to the 1st CD protecting substrate thickness t1 and the 3rd CD protecting substrate thickness t3/due to the different spherical aberrations that produce of wavelength of the 1st light beam and the 3rd light beam.
The zone line of object lens can be described as for the 1st CD, the 2nd video disc recording/regenerate, be not used in the 1st, the 2nd CD common area of the 3rd video disc recording/regeneration.That is to say, object lens by can information recording through the 1st light beam of zone line/again the dried rhizome of rehmannia be concentrated on the information recording surface of the 1st CD, by the 2nd light beam through zone line can information recording and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of the 2nd CD.And not by through zone line the 3rd light beam can information recording/dried rhizome of rehmannia be concentrated on the information recording surface of the 3rd CD again.Preferably the 3rd light beam through object lens zone line forms solar flare on the information recording surface of the 3rd CD.Preferably as shown in Figure 2, in the solar flare forming on the information recording surface of the 3rd CD through the 3rd light beam of object lens from optical axis (or spot central part) laterally successively, have spot central part SCN that light quantity density is high, light quantity density lower than the spot pars intermedia SMD of spot central part, light quantity density higher than spot pars intermedia the spot periphery SOT lower than spot central part.Spot central part is used to the information recording/regeneration of CD, and spot pars intermedia and spot periphery are not used in the information recording/regeneration of CD.Above-mentioned this spot periphery is called solar flare.Wherein, the surrounding of spot central part does not have spot pars intermedia and the type of spottiness periphery, be the surrounding of optically focused spot while forming light large hot spot, and its spot periphery also can be called solar flare.That is to say, can say that the 3rd light beam that preferably passes object lens zone line forms spot periphery on the information recording surface of the 3rd CD.
The neighboring area of object lens can be described as for the 1st video disc recording/regenerate, be not used in the 1st CD reserved area of the 2nd CD and the 3rd video disc recording/regeneration.That is to say, object lens by through neighboring area the 1st light beam can information recording/dried rhizome of rehmannia be concentrated on the information recording surface of the 1st CD again.And not by can information recording through the 2nd light beam of neighboring area and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of the 2nd CD, not by through neighboring area the 3rd light beam can information recording/dried rhizome of rehmannia be concentrated on the information recording surface of the 3rd CD again.Preferably the 2nd light beam and the 3rd light beam through object lens neighboring area forms solar flare on the information recording surface of the 2nd CD and the 3rd CD.The 2nd light beam and the 3rd light beam that preferably pass object lens neighboring area form spot periphery on the information recording surface of the 2nd CD and the 3rd CD.
Preferably the 1st optical path difference is paid to construct and is arranged on more than 70% region of object lens middle section area, more preferably more than 90%.More preferably the 1st optical path difference is paid structure and is arranged on whole of middle section.Preferably the 2nd optical path difference is paid to construct and is arranged on more than 70% region of object lens zone line area, more preferably more than 90%.More preferably the 2nd optical path difference is paid structure and is arranged on whole of zone line.When neighboring area has the 3rd optical path difference to pay structure, preferably the 3rd optical path difference is paid to construct and is arranged on more than 70% region of object lens neighboring area area, more preferably more than 90%.More preferably the 3rd optical path difference is paid structure and is arranged on whole of neighboring area.
It is the general name to the structure of incident beam additional optical path difference that so-called optical path difference in this instructions is paid structure.Optical path difference is paid and in structure, is also comprised that the phase differential of paying phase differential pays structure.In addition, phase differential is paid structure and is comprised diffraction structure.Optical path difference of the present invention is paid and is constructed preferably diffraction structure.Optical path difference is paid structure and is had step, preferably has a plurality of steps.By this step to incident beam additional optical path difference and/or phase differential.It can be the integral multiple of incident beam wavelength that optical path difference is paid the additional optical path difference of structure, can be also the non-integral multiple of incident beam wavelength.Step can be held periodic intervals in optical axis vertical direction and configure, and also can hold the configuration of aperiodicity compartment of terrain in optical axis vertical direction.In addition, when being provided with optical path difference and paying the object lens of structure and be aspheric surface simple lens because light beam to the incident angle of object lens with leaving the height of optical axis difference, so optical path difference is paid step height some differences in each endless belt of structure.For example, when object lens are aspheric surface list convex lens, even pay the optical path difference of same light path difference, paying structure, is also generally more to leave optical axis step just to trend towards increasing.
So-called diffraction structure in this instructions, be have step, hold the general name that makes the structure of light beam convergence or disperse function by diffraction.Comprise for example following structure: by arrange a plurality of units shape centered by optical axis, form, light beam incides each unit in shape, the corrugated that sees through light on every adjacent endless belt produces phase differential, and result forms new corrugated, makes thus light convergence or disperses.Preferably diffraction structure has a plurality of steps, and step can be held periodic intervals in optical axis vertical direction and configure, and also can hold the configuration of aperiodicity compartment of terrain in optical axis vertical direction.In addition, when the object lens that are provided with diffraction structure are aspheric surface simple lens because light beam to the incident angle of object lens with leaving the height of optical axis difference, so step height some differences in each endless belt of diffraction structure structure.For example, when object lens are aspheric surface list convex lens, even make to occur the diffraction structure of identical diffraction number of times diffraction light, be also generally more to leave optical axis step just to trend towards increasing.
Preferred light path difference is paid a plurality of endless belt that structure has the concentric circles centered by optical axis.In general, optical path difference is paid structure can get various cross sectional shapes (cross sectional shape that contains the face of optical axis), and the cross sectional shape that contains optical axis is roughly divided into flame type structure and notch cuttype structure.
Flame type structure is as Fig. 3 (a), (b) as shown in, and having optical path difference, to pay the cross sectional shape that the optical element of structure contains optical axis be zigzag shape.In Fig. 3 example, top is light source side, and below is CD side, is in the aspheric plane of mother, to form optical path difference to pay structure.In flame type structure, the length of the optical axis vertical direction of 1 flame unit is called tooth pitch P (with reference to figure figure 3 (a), (b)).The length of the step of the optical axis parallel direction of flame is called step height B (with reference to Fig. 3 (a)).
Notch cuttype structure, as Fig. 3 (c), (d) as shown in, has optical path difference and pays the cross sectional shape that the optical element of structure contains optical axis and have a plurality of little stepped (being called ladder unit).In this instructions, so-called " V level ", refer in 1 ladder unit of notch cuttype structure, by step to corresponding to (towards) the ring-band shape face (being called again below flat surface) of optical axis vertical direction divides, be divided into every V endless belt face, especially 3 grades of above notch cuttype structures, have small stair and large step.
For example, the optical path difference shown in Fig. 3 (c) is paid structure and is called 5 grades of notch cuttype structures, and the optical path difference shown in Fig. 3 (d) is paid structure and is called 2 grades of notch cuttype structures (being called again scale-of-two structure).Below 2 grades of notch cuttype structures are explained.A plurality of endless belt that comprise the concentric circles centered by optical axis, object lens are formed by the CD side flat surface Pd that is parallel to the light source side flat surface Pc of a plurality of step surface Pa, Pb that optical axis extends and connection adjacent stations terrace Pa, Pb light source side and is connected adjacent stations terrace Pa, Pb CD side containing the cross sectional shape of a plurality of endless belt of optical axis, and light source side flat surface Pc and CD side flat surface Pd are along optical axis vertical direction alternate configurations.
In notch cuttype structure, the length of the optical axis vertical direction of 1 ladder unit is called tooth pitch P.(with reference to figure figure 3 (c), (d)).In addition, the length of the step of the optical axis parallel direction of ladder is called step height B1, B2.During the situation of 3 grades of above notch cuttype structures, there is large step height B1 and small stair height B2 (with reference to Fig. 3 (c)).
Preferred light path difference is paid structure Shi Mou unit shape and is made structure periodically repeatedly.The what is called here " unit shape is done periodically repeatedly " comprises that same shape is with same period work shape repeatedly.And the unit shape of 1 cycle unit is held regularly the cycle elongated shape gradually shortening gradually, is also included among " unit shape is done periodically repeatedly ".
Optical path difference is paid and is constructed while having flame type structure, is that the zigzag shape of unit shape is made shape repeatedly.Can as shown in Fig. 3 (a), be same zigzag shape repeatedly, also can be as shown in Fig. 3 (b), be along with the shape that the elongated shape of the tooth pitch of zigzag shape or tooth pitch shorten forward and gradually of the direction to leaving optical axis.In addition can also form following shape: in certain region, make the step of flame type structure towards optical axis (center) reverse direction, in other region, make the step of flame type structure towards optical axis (center), establish betwixt for switch flame type structure step towards necessary migration region.This switch halfway flame type structure step towards the occasion of structure, can relax endless belt tooth pitch, can suppress optical path difference and pay the transmitance that the foozle of structure causes and reduce.
Optical path difference is paid structure and is had notch cuttype when structure, can get the ladder unit of 5 grades as shown in Fig. 3 (c) and make shape repeatedly etc.And, can be also along with the direction to leaving the optical axis elongated shape of the tooth pitch of ladder unit and the shape that gradually tooth pitch of ladder unit shortens forward and gradually.
The 1st optical path difference is paid structure and the 2nd optical path difference is paid structure and can be located at respectively on the different optical surface of object lens, but is preferably located on same optical surface.Further establish the 3rd optical path difference and pay when structure, be also preferably located at and pay structure with the 1st optical path difference and the 2nd optical path difference is paid on the optical surface that structure is identical.By being located on same optical surface, the eccentric error event that can reduce while manufacturing is preferred.In addition, compare with the face that is located at object lens CD side, preferably the 1st optical path difference is paid structure, the 2nd optical path difference and is paid structure and the 3rd optical path difference and pay structure and be located on the face of object lens light source side.In other words, preferably the 1st optical path difference is paid structure, the 2nd optical path difference and is paid structure and the 3rd optical path difference and pay structure and be located on the optical surface that the absolute value of object lens radius-of-curvature is little.
Subsequent to be located at the 1st optical path difference of middle section pay structure explain.Preferably to pay structure be at least the structure that the 1st base configuration and the 2nd base configuration overlap and form to the 1st optical path difference.
Preferably the 1st base configuration is flame type structure.In addition, the 1st base configuration make through X diffraction light quantity of the 1st light beam of the 1st base configuration be greater than other any number of times diffraction light quantity, make through Y diffraction light quantity of the 2nd light beam of the 1st base configuration be greater than other any number of times diffraction light quantity, make to be greater than through Z diffraction light quantity of the 3rd light beam of the 1st base configuration the diffraction light quantity of other any number of times.Now, X, Y and Z are respectively integer.Preferably X is odd integer.In addition, X is that absolute value is that the step height of words the 1st base configuration of the odd number below 5 is not too large, and so easy manufacture, can suppress the light loss that foozle causes, and the diffraction efficiency change can reduce wavelength variation time, so preferably.
In addition, be preferably located near the 1st its step of base configuration middle section optical axis at least towards the contrary direction of optical axis.So-called " step is towards the contrary direction of optical axis ", refers to the state as shown in Fig. 4 (b).In addition, what is called is located near the 1st base configuration of " at least middle section optical axis ", refers to that above-mentioned X at least approaches most the step of optical axis in the step of odd number.Preferably at least being present in the step that the above-mentioned X between following position and optical axis is odd number, is rightabout towards optical axis, and this position is: the position of half of the boundary from optical axis to middle section zone line in optical axis vertical direction.
For example, be located near the 1st base configuration of zone line of middle section, step also can towards optical axis direction.Can be the shape as shown in Fig. 5 (b), near the 1st base configuration step optical axis, towards optical axis reverse direction, switches halfway, and near zone line, the step of the 1st base configuration is towards optical axis direction.But be preferably located at all steps of the 1st base configuration of middle section all towards the contrary direction of optical axis.
Like this, step by making the 1st base configuration that the diffraction number of times of the 1st light beam is odd integer is towards towards optical axis reverse direction, even thick thick object lens on that axle of BD, DVD and CD3 kind CD exchange use, CD also can fully guarantee operating distance while using, so preferably.
From the axle of BD, DVD and CD3 kind CD exchange use, thick thick object lens also can fully be guaranteed the viewpoint of operating distance when CD is used, and preferably the 1st base configuration is held paraxial strong focus to the 1st light beam.Here " holding paraxial strong focus " means that, while representing the optical path difference function of the 1st base configuration by aftermentioned number 2 formulas, B2h2 is not 0.
Preferably the 2nd base configuration is also flame type structure.The 2nd base configuration make through L diffraction light quantity of the 1st light beam of the 2nd base configuration be greater than other any number of times diffraction light quantity, make through M diffraction light quantity of the 2nd light beam of the 2nd base configuration be greater than other any number of times diffraction light quantity, make to be greater than through N diffraction light quantity of the 3rd light beam of the 2nd base configuration the diffraction light quantity of other any number of times.Now, L, M and N are respectively integer.Preferably L is even-integer.In addition, L is that absolute value is that the step height of words the 2nd base configuration of the even number below 4 is not too large, and so easy manufacture, can suppress the light loss that foozle causes, and the diffraction efficiency change can reduce wavelength variation time, so preferably.
In addition, be preferably located near the 2nd its step of base configuration middle section optical axis at least towards optical axis direction.So-called " step is towards optical axis direction ", refers to the state as shown in Fig. 4 (a).In addition, what is called is located near the 2nd base configuration of " at least middle section optical axis ", refers to that above-mentioned L at least approaches most the step of optical axis in the step of even number.Preferably at least be present in the step that the above-mentioned L between following position and optical axis is even number, towards optical axis direction, this position is: the position of half of the boundary from optical axis to middle section zone line in optical axis vertical direction.
For example, be located near the 2nd base configuration of zone line of middle section, step also can towards optical axis reverse direction.Can be the shape as shown in Fig. 5 (a), near the 2nd base configuration step optical axis, towards optical axis direction, switches halfway, and near zone line, the step of the 2nd base configuration is towards optical axis reverse direction.But be preferably located at all steps of the 2nd base configuration of middle section all towards optical axis direction.
Like this, by the diffraction light overlapping to the 1st light beam generation odd number number of times, at least near the optical axis of middle section step towards rightabout the 1st base configuration of optical axis and the diffraction light to the 1st light beam generation even number number of times, at least near the optical axis of middle section step towards the 2nd base configuration of optical axis direction, compare towards situation about overlapping in the same manner with the step of the 1st base configuration and the 2nd base configuration, the height of backward step of can suppressing to overlap uprises, like this, can suppress the light loss that foozle etc. causes, diffraction efficiency change in the time of can suppressing wavelength variation simultaneously, so preferably.
In addition, not only realized the exchange of BD, DVD and CD3 kind CD, a kind of good object lens of balance that can both maintain the light utilization ratio of high light utilization ratio to BD, DVD and CD3 kind CD can also be provided.For example, in design, can provide a kind of to the diffraction efficiency of wavelength X 1 more than 80%, to the diffraction efficiency of wavelength X 2 more than 60%, to the diffraction efficiency of wavelength X 3 at more than 50% object lens.In addition, by making the step of the 1st base configuration towards towards optical axis reverse direction, can when changing, long wavelength's direction make at wavelength aberration change to the direction of not enough (revising not enough).Like this, the aberration that the temperature that can suppress optical take-up apparatus occurs while rising, when object lens are the situation of plastics, can provide a kind of object lens that also can maintain roadholding when temperature variation.
When object lens are situations of plastics, in order also to maintain roadholding when the temperature variation, 3 spherical aberrations and 5 spherical aberrations that when optimal wavelength is elongated, at object lens, occur be all not enough (revising deficiency).
More preferably the 1st light path is paid structure and is | X|, | Y|, | Z| be respectively 1,1,1 the 1st base configuration and | L|, | M|, | N| is respectively the coincidence structure of 2,1,1 the 2nd base configuration.Form this 1st optical path difference and pay structure, can make the height of step for very low.Like this, can further reduce foozle, can further suppress light loss, the diffraction efficiency change in the time of can further suppressing wavelength variation simultaneously.
The 1st optical path difference from the 1st base configuration and the 2nd base configuration overlap is paid the shape of structure and the viewpoint of step height, | X|, | Y|, | Z| be respectively 1,1,1 the 1st base configuration and | L|, | M|, | N| is respectively the 1st optical path difference that 2,1,1 the 2nd base configuration coincidence forms and pays structure and can show as follows.Be located near the 1st optical path difference middle section optical axis at least and pay structure and have towards the rightabout step of optical axis with towards the step of optical axis direction simultaneously, preferably towards the step height d11 of the rightabout step of optical axis with towards the step height d12 of the step of optical axis direction meet the following conditions formula (1), (2).More preferably in the region-wide formula that meets the following conditions of middle section (1), (2).In addition, when being provided with optical path difference and paying the object lens of structure and be aspheric surface simple lens because light beam to the incident angle of object lens with leaving the height of optical axis and difference, so, even pay the optical path difference of same light path difference, paying structure, is also generally more to leave optical axis and step just trends towards increasing.In following conditional, to the upper limit surplus upper 1.5, be because added the reason of the increase of above-mentioned step height.Object lens refractive index when wherein, n represents the 1st wavelength X 1.
0.6(λ1/(n-1))＜d11＜1.5(λ1/(n-1)) (1)
0.6(λ1/(n-1))＜d12＜1.5(2λ1/(n-1)) (2)
And near the 1st optical path difference that is located at " at least middle section optical axis " is paid structure, refer to have simultaneously at least approach most optical axis towards the rightabout step of optical axis and the optical path difference that approaches the step towards optical axis direction of optical axis most, pay structure.Be at least preferably to have the optical path difference that is present in the step between following position and optical axis to pay structure, this position is: in optical axis vertical direction from optical axis to middle section with half position of the boundary of zone line.
For example, λ 1 is that 390～415nm (0.390～0.415 μ m), n are 1.54～1.60 o'clock, and above-mentioned conditional can represent as follows:
0.39μm＜d11＜1.15μm (12)
0.39μm＜d12＜2.31μm (13)
Coincidence method as the 1st base configuration and the 2nd base configuration, preferably make the tooth pitch of the 1st base configuration and the 2nd base configuration aim at, make the step position alignment of all step positions of the 2nd base configuration and the 1st base configuration, or make the step position alignment of all step positions of the 1st base configuration and the 2nd base configuration.
During the situation of the above-mentioned step position alignment that makes all step positions of the 2nd base configuration and the 1st base configuration, d11, the d12 that preferably the 1st optical path difference is paid structure meet the following conditions formula (1) ', (2) '.More preferably the region-wide formula that meets the following conditions (1) of middle section ', (2) ':
0.6(λ1/(n-1))＜d11＜1.5(λ1/(n-1)) (1)′
0.6(λ1/(n-1))＜d12＜1.5(λ1/(n-1)) (2)′。
For example, λ 1 is that 390～415n m (0.390～0.415 μ m), n are 1.54～1.60 o'clock, and above-mentioned conditional can represent as follows:
0.39μm＜d11＜1.15μm (12)′
0.39μm＜d12＜1.15μm (13)′。
More preferably the formula that meets the following conditions (1) ", (2) ".The region-wide formula that meets the following conditions (1) of middle section ", (2) " more preferably:
0.9(λ1/(n-1))＜d11＜1.5(λ1/(n-1)) (1)″
0.9(λ1/(n-1))＜d12＜1.5(λ1/(n-1)) (2)″。
For example, λ 1 is that 390～415nm (0.390～0.415 μ m), n are 1.54～1.60 o'clock, and above-mentioned conditional can represent as follows:
0.59μm＜d11＜1.15μm (12)″
0.59μm＜d12＜1.15μm (13)″。
By | X|, | Y|, | Z| be respectively 1,1,1 the 1st base configuration and | L|, | M|, | N| is respectively 2,1,1 the 2nd base configuration the 1st optical path difference forming that overlaps and pays structure, because it is not enough (revising not enough) (it is not enough making wavelength characteristic) that the 1st base configuration makes aberration when wavelength is elongated, it is superfluous (revising superfluous) (it is superfluous making wavelength characteristic) that contrary the 2nd base configuration can make aberration when wavelength is elongated, so, the not too large deficiency of wavelength characteristic, also not too large surplus, can access the wavelength characteristic of lucky degree deficiency.So-called " wavelength characteristic of degree deficiency just ", preferably the absolute value of λ rms is below 150.Like this, when object lens are the situation of plastics, the aberration in the time of also can suppressing temperature variation is changed to less, also preferred from this viewpoint.
From the viewpoint of above-mentioned obtaining " wavelength characteristic of degree deficiency just ", preferably to compare with the 2nd base configuration, dominating role is played in the contribution of the 1st base configuration.The viewpoint that plays dominating role from compare the contribution of the 1st base configuration with the 2nd base configuration, preferably the average tooth pitch of the 1st base configuration is less than the average tooth pitch of the 2nd base configuration.With another kind performance, also can be described as towards the tooth pitch between the rightabout step of optical axis, be less than towards the tooth pitch between the step of optical axis direction, also can say in the 1st optical path difference and pay in structure, towards the rightabout number of steps of optical axis, more than the number of steps towards optical axis direction.Preferably the average tooth pitch of the 1st base configuration is in below 1/4 of average tooth pitch of the 2nd base configuration.More preferably make below 1/6.By making the average tooth pitch of the 1st base configuration in below 1/4 of average tooth pitch (preferably below 1/6) of the 2nd base configuration, not only can realize above-mentioned the wavelength characteristic of degree deficiency " just ", also preferred from fully guaranteeing the viewpoint of operating distance of CD.With another kind performance, also can say, in the 1st optical path difference of middle section, pay in structure, be preferably the more than 4 times of number of steps towards optical axis direction towards the rightabout number of steps of optical axis.More preferably more than 6 times.
In addition, the minimum tooth that preferably the 1st optical path difference is paid structure is apart from below 15 μ m.From this viewpoint, the ratio p/f1 of the minimum tooth that preferably the 1st optical path difference is paid structure focal length f1 during with the 1st wavelength X 1 apart from p is below 0.004.The minimum tooth that more preferably the 1st optical path difference is paid structure is apart from below 10 μ m.In addition, the average tooth pitch that preferably the 1st optical path difference is paid structure is below 30 μ m.More preferably make below 20 μ m.By forming this structure, when accessing the wavelength characteristic of above-mentioned lucky degree deficiency, and can make through the 1st optical path difference pay the necessary light for the 3rd optical disc information recording/reproducing that the 3rd light beam of structure produces optimal focus position, separate with the not optimal focus position of light that is not used in the 3rd optical disc information recording/reproducing, can reduce flase drop and go out.So-called average tooth pitch, is the number of steps of paying structure with the 1st optical path difference of middle section, and the 1st optical path difference of removing middle section is paid the value that the total of all tooth pitches of structure obtains.
In object lens preferred axes of the present invention, chromatic aberation is below 0.9 μ m/nm.More preferably make on axle chromatic aberation below 0.8 μ m/nm.Chromatic aberation on words axle that the tooth pitch of the 1st base configuration is too little can be worsened, so, during decision design, be carefully careful, tooth pitch is not caused and make chromatic aberation on axle be greater than 0.9 μ m/nm.From this viewpoint, the ratio p/f1 of the minimum tooth that preferably the 1st optical path difference is paid structure focal length f1 during with the 1st wavelength X 1 apart from p is more than 0.002.And operating distance when fully guaranteeing CD, in preferred axes, chromatic aberation is more than 0.4 μ m/nm.
Preferably by pay the 3rd light beam of structure through the 1st optical path difference, the 2nd optimal focus position of spot light Strong degree the last the second that the 1st optimal focus position that spot light Strong degree that the 3rd light beam forms is the strongest and the 3rd light beam the form formula (14) that meets the following conditions.The optimal focus position here refers to that beam waist is minimum position in certain de-focus region beam waist.The 1st optimal focus position is the optimal focus position for the necessary light of the recording/reproducing of the 3rd CD, and the 2nd optimal focus position is the optimal focus position that is not used in the light beam that light quantity is maximum among the not light of recording/reproducing of the 3rd CD.
0.05≤L/f13≤0.35 (14)
Wherein, f13[m m] represent to pay focal length structure, that form the 3rd light beam of the 1st pinpointed focus, L[mm through the 1st optical path difference] distance between the 1st pinpointed focus and the 2nd pinpointed focus represented.
The formula that more preferably meets the following conditions (14) ':
0.10≤L/f13≤0.25 (14)′。
The 1st optical path difference of narrating above showing in Fig. 6 is paid a preferably example of structure.In Fig. 6, for convenience's sake, the 1st optical path difference is paid structure ODS1 and is located at flat board above, but also can be provided in a side of on aspheric surface list convex lens.| L|, | M|, | it is upper that N| is respectively 2,1,1 the 2nd base configuration BS2, overlapped | X|, | Y|, | Z| is respectively 1,1,1 the 1st base configuration BS1.In addition, the step of the 2nd base configuration BS2 is towards optical axis OA direction, and the step of the 1st base configuration BS1 is towards optical axis OA reverse direction.And can see, the tooth pitch of the 1st base configuration BS1 and the 2nd base configuration BS2 is aimed at, the position of all steps of the 2nd base configuration, is harmonious with the position of the step of the 1st base configuration.In this example, d11=λ 1/ (n-1), d12=λ 1/ (n-1).And in this example, make λ 1=405nm (0.405 μ m), n=1.5592, d11=d12=0.72 μ m.And the average tooth pitch of the 1st base configuration BS1 is less than the average tooth pitch of the 2nd base configuration BS2, the 1st base configuration towards the rightabout number of steps of optical axis, more than the number of steps towards optical axis direction of the 2nd base configuration.
Subsequent to be located at the 2nd optical path difference of zone line pay structure explain.The 2nd optical path difference is paid 3 structures that base configurations coincidence forms that structure is at least the 3rd base configuration and the 4th base configuration and the 5th base configuration.
The 3rd base configuration make through the diffraction light quantity of A time of the 1st light beam of the 3rd base configuration be greater than other any number of times diffraction light quantity, make through the diffraction light quantity of B time of the 2nd light beam of the 3rd base configuration be greater than other any number of times diffraction light quantity, through the diffraction light quantity of C time of the 3rd light beam of the 3rd base configuration, be greater than the diffraction light quantity of other any number of times.In addition, the 4th base configuration make through the diffraction light quantity of D time of the 1st light beam of the 4th base configuration be greater than other any number of times diffraction light quantity, make through the diffraction light quantity of E time of the 2nd light beam of the 4th base configuration be greater than other any number of times diffraction light quantity, through the diffraction light quantity of F time of the 3rd light beam of the 4th base configuration, be greater than the diffraction light quantity of other any number of times.A now, B, C, D, E and F are respectively integer.
The 1st optical path difference is paid structure and the 2nd optical path difference and is paid structure and meet with following formula (15), (16), (17), (18).Like this, can make the optical path difference of middle section and zone line pay the phase differential that structure produces and slightly equate, can reduce the phase differential deviation between middle section and zone line.
X＝A (15)
Y＝B (16)
L＝D (17)
M＝E (18)
More preferably meet again Z=C, N=F.Preferably the 1st base configuration and the 3rd base configuration are that identical structure, the 2nd base configuration and the 4th base configuration is identical structure.
The 5th base configuration make through the diffraction light quantity of 0 time of the 1st light beam of the 5th base configuration be greater than other any number of times diffraction light quantity, make through the diffraction light quantity of 0 time of the 2nd light beam of the 5th base configuration be greater than other any number of times diffraction light quantity, make to be greater than through the diffraction light quantity of G time of the 3rd light beam of the 5th base configuration the diffraction light quantity of other any number of times.G is now the integer beyond 0.By above-mentioned the 5th base configuration that overlaps, like this, the 1st light beam, the 2nd light beam through object lens zone line are not produced to harmful effect, and make not produce between middle section and zone line phase deviation, only make the 3rd light beam form solar flare on the information recording surface of the 3rd CD, can reduce the harmful effect that light does not bring optically focused spot.
Preferably G is ± 1.G is ± 1 o'clock, and preferably the 5th base configuration is the 2 grades of notch cuttype structures (claiming again scale-of-two structure) as shown in Fig. 3 (d).
When the 5th base configuration is 2 grades of notch cuttype structures, preferably the step of its optical axis direction height LB1 provides the step height of the optical path difference that 5 wavelength of the 1st wavelength X 1 divide to the 1st light beam, or the 1st light beam is provided to the step height of the optical path difference that 3 wavelength of the 1st wavelength X 1 divide.By 2 grades of notch cuttypes structure, the 1st light beam is provided to the optical path difference that 5 wavelength of the 1st wavelength X 1 divide, the harmful effect of not wanting light in the time of can reducing CD recording/reproducing, so preferably largelyr.And by making 2 grades of notch cuttypes structure provide to the 1st light beam the optical path difference that 3 wavelength of the 1st wavelength X 1 divide, can reduce the height of the 5th base configuration, so easy manufacture, can reduce and manufacture loss, furthermore, preferred on can preventing the low viewpoint of light utilization ratio.In addition, the change of the diffraction efficiency when suppressing wavelength variations is also preferred in less viewpoint.
That is to say, preferably meet the following conditions formula (19) or (20) of the step of the 5th base configuration height LB1:
0.9(5λ1/(n-1))＜LB1＜1.5(5λ1/(n-1)) (19)
0.9(3λ1/(n-1))＜LB1＜1.5(3λ1/(n-1)) (20)。
In addition, at λ 1, be for example that 390～415n m (0.390～0.415 μ m), n are 1.54～1.60 o'clock, above-mentioned conditional can be expressed as follows:
2.92μm＜LB1＜5.77μm (21)
1.75μm＜LB1＜3.46μm (22)。
Therefore, preferred the 2nd optical path difference is paid structure, is to pay structure same textural with above-mentioned preferred the 1st optical path difference, the structure that the scale-of-two that coincidence G is ± 1 forms.
In addition, preferably the 2nd optical path difference is paid structure as the structure shown in the zone line MD in Figure 10 is upper, on the upper flat table top Pc of the notch cuttype structures of 2 grades, has step.More preferably there are a plurality of steps.Preferably this step is to take the step that a plurality of the 3rd base configurations and single the 4th base configuration be origin.
By establishing the step of a plurality of the 3rd base configurations on the upper flat table top at 2 grades of notch cuttype structures, resin easily arrives the die tip of 2 grades of notch cuttype structures, can improve transfer printing and reduce and manufacture loss, can prevent the reduction of light utilization ratio.And, can make the spot position of diffraction light not, further leave the spot position of necessary diffraction light, can prevent that the diffraction light optically focused because of not wanting from causing that on photo detector producing flase drop goes out, preferred.
In addition, preferably the minimum tooth of the 5th base configuration apart from more than 10 μ m.Preferably tooth pitch is below 100 μ m.By 2 grades of notch cuttypes that do not adopt step height easily to uprise in middle section employing at zone line, construct, can relax tooth pitch, during injection moulding, resin easily enters depths, can reduce and manufacture loss.
On neighboring area, establish the 3rd optical path difference and pay while being configured to, can establish optical path difference arbitrarily and pay structure.Preferably the 3rd optical path difference is paid structure and is had the 6th base configuration.The 6th base configuration make through the diffraction light quantity of P time of the 1st light beam of the 6th base configuration be greater than other any number of times diffraction light quantity, make through the diffraction light quantity of Q time of the 2nd light beam of the 6th base configuration be greater than other any number of times diffraction light quantity, make to be greater than through the diffraction light quantity of R time of the 3rd light beam of the 6th base configuration the diffraction light quantity of other any number of times.And the change of the diffraction efficiency when suppressing wavelength variation, also preferably P below 5.More preferably P is below 2.
Take be used for to the necessary object lens of 1st optical disc reproducing/recorded information as side numerical aperture as NA1, to the necessary object lens of 2nd optical disc reproducing/recorded information as side numerical aperture as NA2 (NA1 > NA2), to the necessary object lens of 3rd optical disc reproducing/recorded information, as side numerical aperture, be NA3 (NA2 > NA3).Preferably NA1 is more than 0.75 below 0.9, more preferably more than 0.8 below 0.9.Especially preferably NA1 is 0.85.Preferably NA2 is more than 0.55 below 0.7.Especially preferably NA2 is 0.60 or 0.65.In addition, preferably NA3 more than 0.4 below 0.55.Especially preferably NA3 is 0.45 or 0.53.
Preferably the middle section of object lens and the boundary of zone line are formed in the part of following (more preferably below the above 1.15NA3 of the 0.95NA3) scope of the above 1.2NA3 of 0.9NA3 while being equivalent to the 3rd light beam use.More preferably the middle section of object lens and the boundary of zone line are formed in the part that is equivalent to NA3.In addition, preferably the zone line of object lens and the boundary of neighboring area are formed in the part of following (more preferably below the above 1.15NA2 of the 0.95NA2) scope of the above 1.2NA2 of 0.9NA2 while being equivalent to the 2nd light beam use.More preferably the zone line of object lens and the boundary of neighboring area are formed in the part that is equivalent to NA2.
Preferably when the 3rd beam condenser of object lens is on the information recording surface of the 3rd CD, spherical aberration at least has the 1 discontinuous portion in place.The scope of the above 1.2NA3 of 0.9NA3 following (more preferably below the above 1.15NA3 of 0.95NA3) when now, preferred discontinuous portion is present in the 3rd light beam use.
In addition, the preferred object lens formula (3) that meets the following conditions:
1.0≤d/f≤1.5 (3)，
Wherein, d represents the thickness (mm) on the optical axis of object lens, the focal length of object lens when f represents the 1st light beam.
While being applied to the CD of the such short wavelength of BD, high NA, in object lens, existing easily generation astigmatism that the problem of eccentric coma aberration also easily occurs, but by the formula of satisfying condition (3), can suppress the generation of astigmatism and eccentric coma aberration.
In addition, due to the formula of satisfying condition (3), object lens become thick object lens thick on its axle, so operating distance easily shortens when CD recording/reproducing, but, however, by establish the 1st optical path difference of the present invention on object lens, pay structure, the operating distance in the time of also can fully guaranteeing CD recording/reproducing, so more remarkable effect of the present invention.
The 1st light beam, the 2nd light beam and the 3rd light beam can be used as directional light and incide on object lens, also can be used as diverging light or bring light together and incide on object lens.During tracking, in order to prevent coma aberration, also preferably make the 1st light beam, the 2nd light beam and the 3rd light beam all as directional light or summary directional light, incide on object lens.By adopting the 1st optical path difference of the present invention to pay structure, can make the 1st light beam, the 2nd light beam and the 3rd light beam all as directional light or summary directional light, incide on object lens, so more remarkable effect of the present invention.When the 1st light beam is directional light or summary directional light, the imaging multiplying power m 1 of object lens when preferably the 1st light beam incides object lens meets following formula (4):
-0.01＜m1＜0.01 (4)。
In addition, making the 2nd light beam is directional light or when slightly directional light incides on object lens, the imaging multiplying power m2 of object lens when preferably the 2nd light beam incides object lens meets following formula (5):
-0.01＜m2＜0.01 (5)。
And while making the 2nd light beam incide object lens as diverging light, the imaging multiplying power m 2 of object lens when preferably the 2nd light beam is to object lens incident meet following formula (5) ':
-0.025＜m2≤-0.01 (5)′。
In addition, making the 3rd light beam is parallel beam or when slightly parallel beam incides on object lens, the imaging multiplying power m3 of object lens when preferably the 3rd light beam incides object lens meets following formula (6):
-0.01＜m3＜0.01 (6)。
And while making the 3rd light beam incide object lens as diverging light, the imaging multiplying power m3 of object lens when preferably the 3rd light beam is to object lens incident meet following formula (6) ':
-0.025＜m3≤-0.01 (6)′。
The operating distance of the object optical element while in addition, preferably adopting the 3rd CD (WD) is below the above 1.5mm of 0.15mm.Preferably below the above 0.9mm of 0.3mm.The WD of the object optical element while preferably adopting the 2nd CD is below the above 1.3mm of 0.2mm.The WD of the object optical element while preferably adopting the 1st CD is below the above 1.0mm of 0.25mm.
The optical information recording regenerator the present invention relates to, has the optical disc apparatus with above-mentioned optical take-up apparatus.
The optical disc apparatus being equipped in optical information recording regenerator is explained, and optical disc apparatus has following manner: only have the pallet that carries and can supporting CD, from taking in the optical information recording regenerator body of optical take-up apparatus etc., to outside, take out; Optical disc apparatus body together with taking in optical take-up apparatus etc., takes out to outside.
In the optical information recording regenerator of above-mentioned each mode of employing, be roughly equipped with following component parts, but be not limited to this.They be accommodated in optical take-up apparatus in shell etc., together with shell make the optical take-up apparatus such as inquiry motor that optical take-up apparatus moves to week in CD or periphery drive source, have to the optical take-up apparatus of the guided way of week in CD or periphery guide optical take-up apparatus shell etc. and transfer means, and carry out Spindle Motor that optical disk rotary gets etc.
In the former mode, except above-mentioned each component parts, also be provided with the pallet that carries and can supporting CD, and be used for making loader mechanism that pallet slides etc., in the latter's mode, there is no pallet and loader mechanism, preferably each component parts is arranged on the base drawer that is equivalent to extract out to outside.
The effect of invention
According to the present invention, even thick thick object lens on that axle of BD, DVD and CD3 kind CD exchange use also can fully be guaranteed operating distance when CD is used.And, can suppress optical path difference and pay the bench height of structure and uprise, the light loss that can suppress to follow the foozle that highly raises etc. to cause, and the change of the diffraction efficiency can suppress wavelength variation time.In addition, can provide a kind of good object lens of balance that can both maintain the light utilization ratio of high light utilization ratio to BD, DVD and CD3 kind CD any.Also be conducive in addition path.In addition, the aberration occurring in the time of can suppressing the rising of optical take-up apparatus temperature, when object lens are plastics, can provide a kind of object lens that also can maintain roadholding when temperature variation.By above-mentioned effect, the enough general object lens of energy carry out the recording/reproducing of BD, DVD and CD3 kind CD well.
Accompanying drawing explanation
Fig. 1: the view of the present embodiment single lens objective OL seeing at optical axis direction.
Fig. 2: the view of the spot forming on the information recording surface of the 3rd CD through the 3rd light beam of object lens.
Fig. 3: (a)-(d) optical path difference is paid the schematic cross-section of the axis direction of structure example.
Fig. 4: be (a) that step is that step is towards the schematic diagram of optical axis reverse direction state towards optical axis direction state, (b).
Near Fig. 5: be (a) is that step is towards optical axis direction optical axis, switch halfway, to being that step is towards the rightabout shape schematic diagram of optical axis near zone line, (b) be is that step is towards optical axis reverse direction near optical axis, switch halfway, to being that step is towards the shape schematic diagram of optical axis direction near zone line.
Fig. 6: the 1st optical path difference is paid the concept map of structure.
Fig. 7: can carry out definitely to the BD of different discs, DVD, CD the structure generalized schematic of the present embodiment optical take-up apparatus PU1 of information recording and/or regeneration.
Fig. 8: (a)-(c) spherical aberration diagram of embodiment 1.
Fig. 9: (a)-(c) schematic diagram of the wavelength interdependence of the diffraction efficiency of embodiment 1.
Figure 10: concept sectional view when the 1st optical path difference of embodiment 1 is paid to structure, the 2nd optical path difference and paid structure, the 3rd optical path difference and pay structure and be located on flat-panel component.
[symbol description]
AC1 2 shaft drives
BS polarization spectro instrument
CN middle section
COL collimation lens
DP dichroism prism
LD1 the 1st semiconductor laser or bluish violet semiconductor laser
LD2 the 2nd semiconductor laser
LD3 the 3rd semiconductor laser
LDP laser cell
MD zone line
OL object lens
OT neighboring area
PD photo detector
PL1 protective substrate
PL2 protective substrate
PL3 protective substrate
PU1 optical take-up apparatus
QWP λ/4 wave plate
RL1 information recording surface
RL2 information recording surface
RL3 information recording surface
SEN sensing lens
Embodiment
Referring to accompanying drawing, embodiments of the present invention are described.Fig. 7 can carry out definitely to the BD of different discs, DVD, CD the structure generalized schematic of the present embodiment optical take-up apparatus PU1 of information recording and/or regeneration.This optical take-up apparatus PU1 can be equipped on optical information recording regenerator.Here the 1st CD of take is CD as BD, the 2nd CD as DVD, the 3rd CD.The present invention is not limited to present embodiment.
Optical take-up apparatus PU1 has object lens OL, λ/4 wave plate QWP, collimation lens COL, polarization spectro instrument BS, dichroism prism DP, the 1st semiconductor laser LD1 (the 1st light source) of luminous ejaculation wavelength X 1=405nm laser beam (the 1st light beam) when BD is carried out to information recording/regeneration, when DVD is carried out to information recording/regeneration the 2nd semiconductor laser LD2 (the 2nd light source) of luminous ejaculation wavelength X 2=660nm laser beam (the 2nd light beam) and when CD is carried out to information recording/regeneration the 3rd semiconductor laser LD3 of luminous ejaculation wavelength X 3=785nm laser beam (the 3rd light beam) integrated laser cell LDP, sensing lens SEN, as photo detector PD of optical detector etc.
As shown in Figure 1, the single lens objective OL of present embodiment on light source side aspherics face, has formed to concentric circles middle section CN, its zone line MD and its neighboring area OT around around containing optical axis centered by optical axis.Although do not illustrate,, on middle section CN, form the 1st optical path difference of having done to describe in detail and paid structure, on zone line MD, form the 2nd optical path difference of having done to describe in detail and paid structure.In addition, on the OT of neighboring area, form the 3rd optical path difference and paid structure.In present embodiment, it is flame type diffraction structure that the 3rd optical path difference is paid structure.In addition, the object lens of present embodiment are plastic lenss.Upper the 1st optical path difference forming of middle section CN of object lens OL is paid structure as shown in Figure 6, it is the structure that the 1st base configuration and the 2nd base configuration overlap and form, the 1st base configuration makes to be greater than through the diffraction light quantity of-1 time of the 1st light beam of the 1st base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of-1 time of the 2nd light beam of the 1st base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of-1 time of the 3rd light beam of the 1st base configuration the diffraction light quantity of other any number of times, at least be located near the 1st base configuration of optical axis of middle section CN, its step is towards the contrary direction of optical axis (holding negative strong focus), the 2nd base configuration makes to be greater than through the diffraction light quantity of 2 times of the 1st light beam of the 2nd base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of 1 time of the 2nd light beam of described the 2nd base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of 1 time of the 3rd light beam of described the 2nd base configuration the diffraction light quantity of other any number of times, at least be located near the 2nd base configuration of optical axis of middle section CN, its step is towards optical axis direction (holding positive strong focus), on axle, chromatic aberation is below 0.9 μ m/nm.
The divergent beams of the 1st light beam (λ 1=405nm) penetrating from bluish violet semiconductor laser LD1, as shown by the solid line, through dichroism prism DP, through after polarization spectro instrument BS, through collimation lens COL, become directional light, by λ/4 wave plate QWP, from straight line polarisation transformation, be circular polarization, through there is no illustrated aperture, its beam diameter, by regulation, does not incide on object lens OL.By the middle section of object lens OL and the light beam of zone line and neighboring area optically focused, via the protective substrate PL1 of thickness 0.1mm, become the spot forming on the information recording surface RL1 of BD.
The folded light beam of modulating through information track on information recording surface RL1, after again seeing through object lens OL and there is no illustrated aperture, by λ/4, wave plate QWP is transformed to straight line polarization from circular polarization, through collimation lens COL, be changed to converging beam, at polarization spectro instrument, BS is reflected, and via sensing lens, SEN brings together on the sensitive surface of photo detector PD.Then use the output signal of photo detector PD, by 2 shaft drive AC1, make object lens OL focusing, follow the tracks of, can read thus the information of the upper record of BD.When the 1st light beam produces wavelength variation, and when thering is the BD of a plurality of information recording layers and carry out recording/reproducing, can by make collimation lens COL as multiplying power change means in optical axis direction displacement, change and incide the angle of divergence of the light beam on object optical element OL or bring angle together, revise thus the spherical aberration that results from wavelength variation and different information recording layer and produce.
The divergent beams of the 2nd light beam (λ 2=660nm) penetrating from the semiconductor laser LD2 of laser cell LDP, shown in dotted line, at dichroism prism, DP is reflected, through polarization spectro instrument BS, collimation lens COL, by λ/4, wave plate QWP is circular polarization from straight line polarisation transformation, incides on object lens OL.By the middle section of object lens OL and zone line optically focused (through the light beam of neighboring area by solar flare; form spot periphery) light beam; via the protective substrate PL2 of thickness 0.6mm, become the spot forming on the information recording surface RL2 of DVD, form spot central part.
The folded light beam of modulating through information track on information recording surface RL2, after again seeing through object lens OL, by λ/4, wave plate QWP is transformed to straight line polarization from circular polarization, through collimation lens COL, be changed to converging beam, at polarization spectro instrument, BS is reflected, and via sensing lens, SEN brings together on the sensitive surface of photo detector PD.Then use the output signal of photo detector PD, can read the information of the upper record of DVD.
The divergent beams of the 3rd light beam (λ 3=785nm) penetrating from the semiconductor laser LD3 of laser cell LDP, as shown in dot-and-dash line, at dichroism prism, DP is reflected, through polarization spectro instrument BS, collimation lens COL, by λ/4, wave plate QWP is circular polarization from straight line polarisation transformation, incides on object lens OL.(by solar flare, forming spot periphery through the light beam of zone line and neighboring area) light beam by the middle section optically focused of object lens OL, via the protective substrate PL3 of thickness 1.2mm, becomes the spot forming on the information recording surface RL3 of CD.
The folded light beam of modulating through information track on information recording surface RL3, after again seeing through object lens OL, by λ/4, wave plate QWP is transformed to straight line polarization from circular polarization, through collimation lens COL, be changed to converging beam, at polarization spectro instrument, BS is reflected, and via sensing lens, SEN brings together on the sensitive surface of photo detector PD.Then use the output signal of photo detector PD, can read the information of the upper record of CD.
Embodiment
To can be used in the embodiment of above-mentioned embodiment, explain below.After (comprising lens data in table) sometimes use E (for example 2.5 * E-3) to represent 10 power exponent (for example 2.5 * 10-3).In addition, the optical surface of object lens is formed and is: by several 1 formulas respectively the regulation of the numerical expression after coefficient shown in substitution table, around the axisymmetric aspheric surface of optical axis.
[several 1]
X ( h ) = ( h 2 / r ) 1 + 1 - ( 1 + &kappa; ) ( h / r ) 2 + &Sigma; i = 0 10 A 2 i h 2 i
Wherein, X (h) is the axle (with the direct of travel of light for just) of optical axis direction, and κ is circular cone coefficient, A 2ibe asphericity coefficient, h is the height that leaves optical axis, and r is paraxial radius-of-curvature.
In addition, adopt the occasion of the embodiment of diffraction structure, the optical path difference that diffraction structure provides each wavelength light beam, in the optical path difference function in several 2 formulas, shown in substitution table, the numerical expression after coefficient is stipulated.
[several 2]
Φ＝mλ∑B 2ih 2i
(mm of unit)
H is the height that leaves optical axis, and λ is the wavelength of incident beam, and m is diffraction number of times, B 2iit is optical path difference function coefficients.
Embodiment 1
The object lens of embodiment 1 are plastics simple lenses.The 1st optical path difference of showing embodiment 1 in Fig. 6 is paid the concept map of structure (Fig. 6 is different from the true form of embodiment 1, only concept map).The 1st optical path difference of embodiment 1 is paid structure, on middle section region-wide, | L|, | M|, | it is upper that N| is respectively the 2nd base configuration BS2 of 2,1,1 flame type diffraction structure, overlaps | X|, | Y|, | Z| is respectively the 1st base configuration BS1 of 1,1,1 flame type diffraction structure and the optical path difference that forms is paid structure.In addition, the step of the 2nd base configuration BS2 is towards optical axis OA direction, and the step of the 1st base configuration BS1 is towards optical axis OA reverse direction.And know, the tooth pitch of the 1st base configuration BS1 and the 2nd base configuration BS2 is harmonious, the position of the position of all steps of the 2nd base configuration and the step of the 1st base configuration is harmonious.And the average tooth pitch of the 1st base configuration BS1 is less than the average tooth pitch of the 2nd base configuration BS2, the 1st base configuration towards the rightabout number of steps of optical axis, more than the number of steps towards optical axis direction of the 2nd base configuration.
The 1st optical path difference of embodiment 1 pay structure meet the following conditions formula (1) ', (2) '.D11 is the step height towards the rightabout step of optical axis, and d12 is the step height towards the step of optical axis direction.
0.9(λ1/(n-1))＜d11＜1.5(λ1/(n-1)) (1)′
0.9(λ1/(n-1))＜d12＜1.5(λ1/(n-1)) (2)′
The λ 1 of embodiment 1 is 405nm (0.405 μ m), and n is 1.5592, the formula so step height d11, d12 meet the following conditions:
0.65μm＜d11＜1.09μm
0.65μm＜d12＜1.09μm。
The 2nd optical path difference of embodiment 1 is paid structure, on zone line region-wide, the textural of 3rd base configuration identical with the 1st base configuration and 4th base configuration identical with the 2nd base configuration that overlapped, has further overlapped the 5th base configuration and the optical path difference that forms is paid structure.The 5th base configuration of embodiment 1, be make through the diffraction light quantity of 0 time of the 1st light beam of the 5th base configuration be greater than other any number of times diffraction light quantity, make through the diffraction light quantity of 0 time of the 2nd light beam of the 5th base configuration be greater than other any number of times diffraction light quantity, make through the 3rd light beam of the 5th base configuration ± the diffraction light quantity of 1 time is greater than the notch cuttype of 2 grades (scale-of-two structure) structure of the diffraction light quantity of other any number of times.
The lens data that shows embodiment 1 in table 1.
[table 1]
The focal length f of object lens 1=2.20mm f 2=2.38mm f 3=2.45mm
Numerical aperture NA1:0.85 NA2:0.60 NA3:0.47
Multiplying power m1:0 m2:0 m3:0
Wavelength characteristic+5nm
ΔSA3：-0.105
ΔSA5：-0.024
SAH：0.015 |d(n-1)/λ 1*N|：45
And according to the lens data of embodiment 1, designed the shape of actual object lens.At table 2, show the data of this true form in to 6.By table 2 to the data substitution shown in 6 (continuously) by the numerical expression shown in several 3 formulas, can obtain thus the data of each endless belt true form.Table 2 is in 6, and hs represents the height (mm) that each endless belt starts, and h1 represents the height (mm) that each endless belt finishes.
[several 3]
x＝A 0+A 2×h 2+A 4×h 4+A 6×h 6
H is illustrated in the height that leaves optical axis in optical axis vertical direction.And the concept sectional view when having shown the 1st optical path difference of establishing embodiment 1 on flat-panel component paying structure, the 2nd optical path difference and pay structure, the 3rd optical path difference and pay structure in Figure 10.Being provided with the 1st optical path difference, to pay the middle section of structure be CN, and being provided with the 2nd optical path difference, to pay the zone line of structure be the region representing with MD, and being provided with the 3rd optical path difference, to pay the neighboring area of structure be the region representing with OT.
[table 2]
[table 3]
[table 4]
[table 5]
[table 6]
As shown in table 1, in embodiment 1, m1=0, m2=0, m3=0.In addition, d/f=2.67/2.2=1.21.Even be difficult to obtain the object lens of operating distance during, CD large as this d/f, the operating distance during as CD, embodiment 1 has also successfully guaranteed 0.359mm.In addition, pay the minimum tooth of structure apart from being about 7.6 μ m from table 2 to 6, the 1 optical path differences, average tooth pitch is about 14.39 μ m.Therefore, p/f1=0.00345.
In addition, the diffraction efficiency of the object lens of embodiment 1, during BD is 87.3%, during DVD is 74.6%, is 60.9% during CD, to any CD, can both balance obtain well high diffraction efficiency.
The spherical aberration diagram that shows embodiment 1 in Fig. 8.Spherical aberration diagram when Fig. 8 (a) is BD, spherical aberration diagram when Fig. 8 (b) is DVD, spherical aberration diagram when Fig. 8 (c) is CD.In each spherical aberration diagram, L M is the light of comparing the diffraction number of times that maximum light quantities occur with the diffraction light of other any number of times, is the spherical aberration of key light, the 1st, light quantity is less than the light of main diffraction of light number of times, the spherical aberration of not wanting light 1 that expression is not used in optical disc information recording/reproducing, 2 be also the light quantity light that is less than main diffraction of light number of times, represent to be not used in the other not spherical aberration of light 2 of optical disc information recording/reproducing, 3 is also the light that light quantity is less than main diffraction of light number of times, represents to be not used in the other not spherical aberration of light 3 again of optical disc information recording/reproducing.As shown in Figure 8, can know under m1=0, m2=0, m3=0 situation, in necessary numerical aperture, keep good spherical aberration, to any CD, can both carry out well information recording/regeneration.In addition, as can be seen from Figure 8, can access the preferred result that does not produce phase deviation between middle section and zone line.
On the axle of embodiment 1, chromatic aberation is 0.67 μ m/nm.In addition, the wavelength characteristic of embodiment 1 and temperature characterisitic are shown in table 7.3 spherical aberrations during the 1st optical source wavelength change+5nm are that-0.105 λ rms, 5 spherical aberrations are-0.024 λ rms.3 spherical aberrations when in addition, environment temperature rising+30 is spent are that 0.114 λ rms, 5 spherical aberrations are 0.025 λ rms.They improve by multiplying power correction.Multiplying power correction refers to the multiplying power correction by mobile collimation lens.
[table 7]
Δλ+5nm Before multiplying power correction After multiplying power correction
SA3 -0.105 0.000
SA5 -0.024 -0.006
SA7 -0.010 -0.006
ΔT+30deg Before multiplying power correction After multiplying power correction
SA3 0.114 0.000
SA5 0.025 0.005
SA7 0.002 -0.002
Can know, 3 spherical aberrations and 5 spherical aberrations that embodiment 1 occurs when wavelength is elongated are all not enough (revising not enough).In addition, can know, obtain the little preferred result of absolute value of temperature characterisitic, preferred the amount of movement of collimation lens and the viewpoint of correction resolution.
The wavelength interdependence of showing the diffraction efficiency of embodiment 1 in Fig. 9.As can be seen from Figure 9, the change of the diffraction efficiency while all having suppressed wavelength variation during any one situation of BD, DVD, CD, for less, has obtained preferred result.
The present invention is not limited to the embodiment recording in instructions, and the clear and definite the present invention of the embodiment that the personnel of being engaged in of this area can record from this instructions and thought also comprises other embodiment and variation.The record of instructions and embodiment, only, only as illustration, scope of the present invention is shown by technical scheme.

Claims (15)

1. object lens, for thering is the 1st light source of the 1st light beam that penetrates the 1st wavelength X 1, penetrate the 2nd light source of the 2nd light beam of the 2nd wavelength X 2, penetrate the 3rd light source of the 3rd light beam of the 3rd wavelength X 3, and there is with described the 1st light beam information recording and/or the regeneration of the 1st CD that thickness is the protective substrate of t1, with described the 2nd light beam, there is information recording and/or the regeneration of the 2nd CD that thickness is the protective substrate of t2, with described the 3rd light beam, there are the 3rd information recording of CD of protective substrate that thickness is t3 and/or the object lens of the optical take-up apparatus of regeneration, it is characterized in that,
The optical surface of described object lens at least has the zone line of middle section, described its central area, described zone line neighboring area around,
Described middle section has the 1st optical path difference and pays structure,
Described zone line has the 2nd optical path difference and pays structure,
Described object lens by can information recording through described the 1st light beam of described middle section and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 1st CD, by described the 2nd light beam through described middle section can information recording and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 2nd CD, by described the 3rd light beam through described middle section can information recording and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 3rd CD
Described object lens by can information recording through described the 1st light beam of described zone line and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 1st CD, by described the 2nd light beam through described zone line can information recording and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 2nd CD, can not information recording by described the 3rd light beam through described zone line and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 3rd CD
Described object lens by can information recording through described the 1st light beam of described neighboring area and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 1st CD, can not information recording by described the 2nd light beam through described neighboring area and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 2nd CD, can not information recording by described the 3rd light beam through described neighboring area and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of described the 3rd CD
It is at least to overlap the structure of the 1st base configuration and the 2nd base configuration that described the 1st optical path difference is paid structure,
Described the 1st base configuration makes to be greater than through the diffraction light quantity of X time of the 1st light beam of described the 1st base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of Y time of the 2nd light beam of described the 1st base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of Z time of the 3rd light beam of described the 1st base configuration the diffraction light quantity of other any number of times, described the 2nd base configuration makes to be greater than through the diffraction light quantity of L time of the 1st light beam of described the 2nd base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of M time of the 2nd light beam of described the 2nd base configuration the diffraction light quantity of other any number of times, make to be greater than through the diffraction light quantity of N time of the 3rd light beam of described the 2nd base configuration the diffraction light quantity of other any number of times,
It is at least to overlap the structure of the 3rd base configuration and the 4th base configuration and the 5th base configuration that described the 2nd optical path difference is paid structure,
Described the 3rd base configuration make through the diffraction light quantity of A time of the 1st light beam of described the 3rd base configuration be greater than other any number of times diffraction light quantity, make to be greater than through the diffraction light quantity of B time of the 2nd light beam of described the 3rd base configuration the diffraction light quantity of other any number of times
Described the 4th base configuration make through the diffraction light quantity of D time of the 1st light beam of described the 4th base configuration be greater than other any number of times diffraction light quantity, make to be greater than through the diffraction light quantity of E time of the 2nd light beam of described the 4th base configuration the diffraction light quantity of other any number of times
Described the 5th base configuration make through the diffraction light quantity of 0 time of the 1st light beam of described the 5th base configuration be greater than other any number of times diffraction light quantity, make through the diffraction light quantity of 0 time of the 2nd light beam of described the 5th base configuration be greater than other any number of times diffraction light quantity, make to be greater than through the diffraction light quantity of G time of the 3rd light beam of described the 5th base configuration the diffraction light quantity of other any number of times
The relation of λ 1, λ 2, λ 3 is λ 2> λ 1, λ 3> λ 2; The relation of t1, t2, t3 is t1<t2, t2<t3,
X, Y, Z, L, M, N, A, B, D and E are integers, and G is the integer beyond 0, meets following formula:
X=A (15)
Y=B (16)
L=D (17)
M=E (18)。
2. as the object lens of recording in claim 1, it is characterized in that, meet following formula:
G=±1 (23)。
3. as the object lens of recording in claim 1, it is characterized in that, described the 5th base configuration is 2 grades of notch cuttype structures.
4. as the object lens of recording in claim 3, it is characterized in that, described 2 grades of notch cuttypes structure has the step of the optical path difference that 5 wavelength that described the 1st light beam is provided to described the 1st wavelength X 1 divide.
5. as the object lens of recording in claim 3, it is characterized in that, described 2 grades of notch cuttypes structure has the step of the optical path difference that 3 wavelength that described the 1st light beam is provided to described the 1st wavelength X 1 divide.
6. as the object lens of recording in claim 3, it is characterized in that, on the upper flat table top of described 2 grades of notch cuttypes structure, thering is the step of single described the 4th base configuration and a plurality of described the 3rd base configurations.
7. as the object lens of recording in claim 3, it is characterized in that, the minimum tooth of described the 5th base configuration is apart from more than 10 μ m.
8. as the object lens of recording in claim 1, it is characterized in that, described L and D are even numbers, and described X and A are odd numbers.
9. as the object lens of recording in claim 8, it is characterized in that, described L and D be absolute value at the even number below 4, described X and A are that absolute value is at the odd number below 5.
10. as the object lens of recording in claim 1, it is characterized in that,
Described the 1st base configuration, described the 2nd base configuration, described the 3rd base configuration and described the 4th base configuration are flame type structures,
At least be located near described the 1st base configuration optical axis of described middle section, its step is towards the contrary direction of optical axis,
Near described the 2nd base configuration of optical axis that is at least located at described middle section, its step is towards the direction of optical axis.
11. as the object lens of recording in claim 10, it is characterized in that, described the 1st base configuration and described the 3rd base configuration, their all steps are all towards optical axis reverse direction, described the 2nd base configuration and described the 4th base configuration, their all steps are all towards optical axis direction.
12. as the object lens of recording in claim 1, it is characterized in that, formula meets the following conditions:
1.0≤d／f≤1.5 (3)
Wherein, d represents the thickness on the optical axis of described object lens, and unit is mm, the focal length of described object lens when f represents object lens described in described the 1st light beam incident, and unit is mm.
13. as the object lens of recording in claim 1, it is characterized in that, formula meets the following conditions:
-0.01<m1<0.01 (4)
-0.01<m2<0.01 (5)
-0.01<m3<0.01 (6)
Wherein, when m1 represents that described the 1st light beam incides described object lens described in the multiplying power of object lens, when m2 represents that described the 2nd light beam incides described object lens described in the multiplying power of object lens, when m3 represents that described the 3rd light beam incides described object lens described in the multiplying power of object lens.
14. 1 kinds of optical take-up apparatus, is characterized in that, have the object lens of recording in any one of claim 1 to 13.
15. 1 kinds of optical information recording regenerators, is characterized in that, have the optical take-up apparatus of recording in claim 14.
CN201010170114.2A 2009-05-07 2010-05-04 Objective lens, optical pickup apparatus, and optical information recording reproducing apparatus Expired - Fee Related CN101901607B (en)

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US20100284261A1 (en) 2010-11-11
US8310909B2 (en) 2012-11-13

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